A method is presented for measuring the amplitude and group delay of the transfer function of a system using single-channel measurements. The technique is based on the use of broadband signals. A noise analysis is included to calculate the accuracy of the measurement results for a given signal-to-noise (S/N) ratio. The experiments showed that it is possible to get useful results, even if the S/N ratio is very low. As a main requirement, the digitizer has to have a sufficiently long memory to allow the use of time-averaging techniques